Does Low-E glass affect houseplants?

Does Low-E glass affect houseplants?

Many of our customers here in the Albuquerque and Santa Fe area ask us if the growth of plants inside the home will be affected by new windows with Low-E glass (low thermal emissivity glass). In this article, we will explain factors vital for plant growth and the impact of low-E glass for this growth. If you do not know what Low-E glass is, read our blog article what are low-E windows and why buy them.

A healthy plant that grows behind glass is the result of many different factors; such as type of plant, internal room temperature and humidity where the plant is located, and also the percentage of daylight coming through the glass at specific times of day. Let’s take a high-school refresher crash course on plant growth!

Solar radiant energy as visible light acts as a fuel source for green plants. Through photosynthesis, plants use visible light to change carbon dioxide and water into simplified sugars and starches which they use for nutrition. Though this light is important, a green plant does not use all light available for its growth. Although sunlight looks white, it’s really composed of separate wavelengths each with their own color, and plants will use some of the wavelengths more than others. Most of the important photochemical processes in a plant use the red and blue wavelengths of the spectrum for ideal growth. Red light, for example, stimulates leaf and stem growth while blue light regulates plant enzymes, the respiratory process, and encourages low, dark, thick green leaves. Giving your houseplants the right balance of red and blue light is important for successful growth. As we all know, some plants grow best in full or partial shade with no direct solar radiation while some prefer full sunlight. The hours of daylight, the window size, and degree or type of shading will determine the amount of light available for plant growth.

Taking all of this into account, it is actually best for plants to grow behind glazing that has a neutral daylight transmittance with no strong coloration. Most Low-E glass transmits 59% to 75% of visible light, as compared to the visible light coming through a (non low-E) double glazed clear insulated unit which is about 81%. Meaning, that going from clear to Low-E does not affect much of the daylight intake. Low-E glass also blocks Ultra Violet Radiation which can be harmful to plants in large amounts. The internal temperature is another important factor. A Low-E window that does not transmit as much solar heat will keep your plants warmer at night while at the same time protecting them from heat during the day.